Bump pillow from 7.1.2 to 8.1.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 7.1.2 to 8.1.1.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@7.1.2...8.1.1)

Signed-off-by: dependabot[bot] <support@github.com>

requirements/requirements.txt

@@ -10,7 +10,7 @@ pyserial==3.0
 psutil==5.6.6
 pocketsphinx==0.1.0
 inflection==0.3.1
-pillow==7.1.2
+pillow==8.1.1
 python-dateutil==2.6.0
 fasteners==0.14.1
 PyYAML==5.4